1. Field of the Invention
This invention relates to a welding data acquisition and control system and more particularly to a portable, digital computer-based welding data acquisition and control system using a passive backplane with staggered connectors on both sides of the backplane that receive and hold circuit boards onto which the central processing unit and other components of a digital computer are mounted and which provide for the use of operator and sensor input for monitoring the welding process and operator and automated control output for use by the operator or for direct control of the welding process.
2. Background
The use of computers for the input and control of the welding process is known in the art. Such use includes those applications where the computer is used to monitor one or more input variables and provide data to an operator to change the welding process Other use includes applications where the computer is used not only to monitor one or more input variables but also to automatically control the welding process.
Illustrative of computer use to monitor input data and provide the operator with data on the welding process include the following.
U.S. Pat. No. 4,996,409 to Paton et al. discloses the use of a computer to monitor the voltage, current, welding speed, feed rate and slope of the electrode in an arc welding process which data is processed with a resultant output of audible signals that provide information to the operator of incremental changes in the monitored parameters. U.S. Pat. No. 4,375,026 to Kearney discloses voltage, current and travel speed sensors that are compared with reference data using analog computer modules to set off high or low alarms. U.S. Pat. No. 4,555,614 to Morris et al. discloses a speed and temperature sensor that is processed by a computer and compared with acceptable rates of change of weld temperature. A light indicator in the operator's helmet indicates to the operator whether the speed of the welding torch is too slow, within range, or too fast so that the operator can adjust the speed accordingly.
UK Patent Application GB 2,173,316 A to Brown discloses a welding monitor for monitoring voltage, current, gas flow or wire feed speed and comparing them with predetermined values to indicate by means of light emitting diodes when the process is within acceptable ranges of the monitored variables.
Patents illustrative of the use of computer processing to monitor input variables and automatically control the welding process include:
U.S. Pat. No. 4,187,020 to Chande et al. uses an IBM PC/AT computer for determining cooling rates to effect control of a robotic and laser controller. This system also employs a seam tracking/imaging processing module to control movement of a robotic arm. U.S. Pat. No. 4,651,283 to Sciaky et al. discloses a computer system for determining the special coordinates of a work piece which in turn is used to control the position of a welding device. U.S. Pat. No. 4,490,795 to Calcagno shows an apparatus for monitoring current, voltage and firing angle of a welding gun to automatically control various parameters of the welding process including the firing angle and the number of cycles of the welding process.
U.S. Pat. No. 4,482,798 to Hurlebaus et al. describes an automatic electric welding system that uses welding speed, current and voltage in combination to produce an electrical signal that is used to control a variable of the welding operation, for example, the wire feed rate. U.S. Pat. No. 4,258,425 to Ramsey et al. describes a computer driven apparatus that senses the seam contour of a part and then is able to control the position of an arch welder along the seam contour of a similar part. U.S. Pat. No. 4,104,724 to Dix et al. discloses a digital welder control system that provides diagnostics or common welding problems such as half-cycling, low water flow, etc. as well as a compensator control to automatically increase weld heat to compensate for electrode mushrooming. U.S. Pat. No. 4,063,075 to Collom uses a minicomputer to monitor and control a large number of welding heads. U.S. Pat. No. 4,024,371 to Drake shows a monitoring and control system for a pulse-type welding that senses voltage and current in order to control the welding process by shortening or lengthening the heating or cooling cycles.
Typically such computer driven processes have used computer systems that are bulky and unsuitable for field operations such as pipeline, plant and building construction and modification, and welded part diagnosis and repair. Furthermore, the rapid change in computer and associated component technology requires that all components of a computer system including the central processing unit be easily interchangeable and upgradeable to take maximum advantage of changes and improvements in welding technology. These problems are only beginning to be addressed in the welding filed although some development has occurred in other areas. For example, in reducing the size of a retail, point of sale, terminal, Landis et al (U.S. Pat. No. 4,901,205) uses a bus board to provide communication between a processor board and additional circuit boards that are placed in a staggered configuration on opposite sides of the bus board Such a configuration allows for a smaller electronic enclosure The Landis bus board serves as a data bus between peripheral circuit boards which are plugged into the bus. However, the Landis design hinders plugging the bus board into the processor board socket in view of the obstruction of the view of the mating of the bus board and the processor socket by the sides of the cabinet housing. Furthermore the Landis configuration does not allow for ready replacement of the main processor or other circuit boards nor does it insure adequate cooling of the various component parts.
U.S. Pat. No. 4,498,717 to Reimer discloses a circuit board interconnect arrangement in which some of the wiring boards are staggered in alternating positions on either side of an interconnect plane. In addition, Reimer requires the use of backplanes and cross-connect boards in a complex arrangement.
U.S. Pat. No. 4,834,660 to Cotti discloses a zero-insertion forces interconnect system for intended circuit boards. U.S. Pat. No. 4,708,660 to Claeys et al. discloses a connecting device for electrically and mechanically linking multiple circuit boards arranged into perpendicular stacks. U.S. Pat. No. 4,818,241 to Smoot discloses two sets of circuit boards that are aligned in right angles to each other by means of a circuit board edge connector that utilizes alternating conductive and nonconductive segments.
As is apparent from the above discussion, a wide variety of computer-controlled systems have been developed to monitor and control welding operations To date, these systems have been essentially dedicated systems for controlling specific welding operations using methodologies that are directed to a particular type of welding or a particular variable in the welding process. Calcagno has made some effort to use a computer system in providing a more generalized welding system; however, even the Landis invention is limited to sixteen welding programs that control a limited number of parameters in single-phased resistance welding application using one or two guns controlled by a group of static switches.
Some effort has been made in reducing the size of enclosures for personal computers while allowing the continued use of standard plug-in boards as exemplified by Landis et al. However, even Landis is directed to a specific application, i.e., a compact, computer housing that plugs into a point-of-sale unit. Furthermore the Landis housing does not allow for ready cooling or easy accessibility when placed in a portable carrying case.
None of the above references suggest a portable welding data acquisition and control system for field use. Nor do they suggest the use of a wide range of operator and sensor inputs as well as a wide range of operator and automated control outputs that are applicable to a wide range of welding processes including robotic operations. As a result, none of the prior art devises afford or suggest a portable welding unit with a multitude of operator and sensor inputs and operator and automated control outputs that are applicable to a wide variety of welding operations including robotic welding not currently available for field use.